Stony Corals

Stony Corals

When we talk about stony corals we often divide them between Long-Polyp Stony (LPS) corals and Short-Polyp Stony (SPS) corals. This division is a division of convenience not one of science. While the lighting requirement for these two is generally vastly different, their other care requirements are not so different. Much of these differences have to do with their natural environment.

LPS Corals

Many of the corals that a placed in this category are not even reef corals, rather they are lagoonal species that are found growing from the sandy bottom rather then growing out of rocks. For this reason, many of the species we keep, fare quite well when placed on the substrate, and many even have skeletal structures that lend them to this placement quite well. A lagoon environment is generally not as "clean" as a reef environment, and thus many LPS corals are much more tolerant of sediments and nutrients in the water. Because many of these species are native to the lagoons, they are from waters that are relatively deeper then the SPS members of the stony coral groups, they are much less demanding for lighting, also the flow in these areas is generally quite low and thus they appreciate the lower flow. LPS corals greatly appreciate being fed on a regular basis as well. While it is not necessary to provide them with food, doing so will greatly aid their health and growth. Because most species are zooxanthalic species, they can survive simply via the nutrients provided them but the zooxanthalae, however because of their larger polyp size, they are capable of taking in larger foods. Many marine hobbyists often feed their LPS corals the same foods they would provide for their more carnivorous fish species. These foods include Mysis Shrimp, Brine Shrimp, chunks of crustacean flesh, and even pieces of fish. Some of the species with much larger mouths such as the Bubble Coral - Plerogyra sinuosa can in fact be fed whole krill and even Silver sides. Something to keep in mind when keeping these corals, and feeding them, is that they are capable of delivering a rather potent sting due to the nemocysts found at the end of their tentacles. Personally I keep mostly LPS corals in my 125gal reef tank, and I maintain them under just 192 watts of Power Compact lighting, and they are doing extremely well.

LPS corals can generally be further divided by skeletal structure as well. There are three main forms of skeletal structure found among these corals: Branching, Ridge, and "Plate." In some cases, the genus will dictate the skeletal type, however in a couple of cases that is not so. The Euphyllia genus contains both Ridge, and Branching corals, in fact, both the Hammer coral (Anchor coral) and the Frogspawn coral come in branching and ridge forms. Most LPS corals for very large skeletons, and as a result are generally slower growing corals. Because these corals have large fleshy polyps on hard stony skeletons, they should not be placed in areas of very high flow as the polyps can easily be damaged. This also mean they should be handled with care and care should be taken not to drop anything, no matter how small, on them. Once the a polyp has been damaged, it often does not recover.

Candy Cane (Branching LPS)

Lobo Brain Coral (Plate Structure LPS)

SPS Corals

SPS corals are considered by many as the crown jewels of the reef. Found on the reef crest, SPS corals come from a clean, bright, high flow area. SPS corals are generally found just below the surface and in some cases, they are even exposed at low tide during certain times of the year in certain areas, and therefore will require bright lighting when kept in the home aquarium. Reef crests are also areas of very high flow, called surge zones. Because of this high flow, nutrients like phytoplankton, and zooplankton are carried though the colonies of SPS corals and they feed quite readily on them. As with LPS, it is not essential that the hobbyist feed SPS corals, it does aid greatly in health and growth. SPS corals are more demanding of water quality then LPS because they do come from such "clean" environments. While both LPS and SPS corals are demanding of Calcium levels and Alkalinity levels, SPS are often much more demanding because of their faster growth rate. Calcium levels for both LPS and SPS should be maintained at 450ppm. Many times, in tanks that are dominated by SPS corals, the use of a Calcium reactor becomes a great asset. SPS corals are much less forgiving than LPS corals, and if they are not provided the proper environment, they will bleach out rather quickly and if they recover at all, it is generally quite slow. The cost of maintaining a SPS dominated tank is generally very high because of the equipment that is generally needed. Most SPS keepers will use Metal Halides, and subsequently a chiller, a calcium reactor, and a RO/DI unit. The setup and operating costs of a predominantly SPS tank, is not something to be attempted by the low budget hobbyist. T5 lighting can also be used for SPS corals, as well as new LED fixtures. These two forms of lighting are both more energy efficient, however the later is still very very expensive to setup.

Like LPS, SPS corals have more than one kind of skeletal structure. Again, there are three main skeleton forms: Branching, Encrusting, and Plate. Acropora species are dominated entirely by branching forms, while Montipora species encompass all three forms. There are more genera then just these two, however these two dominate the hobby, and nature. It is estimated that the Acropora genus accounts for more biomass in the worlds oceans than all other coral genera combined.

While they are very much the same, they are still very different. They both build hard calcium based skeletons, however their care is quite different. Lighting and flow requirements for these two kinds of corals are on opposite ends of the coral care spectrum, and as such they are best not kept in the same aquarium unless proper conditions for both can be supplied. LPS such as Goniopora simply will not survive in a SPS system because of the pristine conditions that are maintained. Both SPS and LPS make stunning displays and will make a tank that any hobbyist would be proud to display.

Montipora Digitata (Branching SPS)

Montipora Cap. (Plate SPS)

Encrusting Montipora